Hearing loss more prevalent than previously thought

By Michael Johnsen

BALTIMORE — Nearly one-fifth of all Americans ages 12 years and older have hearing loss so severe that it may make communication difficult, according to a new study led by Johns Hopkins researchers and published in the Nov. 14 issue of the Archives of Internal Medicine. The findings, thought to be the first nationally representative estimate of hearing loss, suggest that many more people than previously thought are affected by this condition.

The researchers used data from the National Health and Nutritional Examination Surveys, a research program that has periodically gathered health data from thousands of Americans since 1971. The researchers analyzed data from all participants ages 12 years and older, whose hearing was tested during NHANES examinations from 2001 to 2008. Unlike previous estimates, NHANES includes men and women of all races and ages, from cities scattered across the country, so it’s thought to statistically mimic the U.S. population.

Using the World Health Organization’s definition for hearing loss (not being able to hear sounds of 25 decibels or less in the speech frequencies), the researchers found that overall, about 30 million Americans, or 12.7% of the population, had hearing loss in both ears. That number jumps to about 48 million, or 20.3%, for people who have hearing loss in at least one ear. These numbers far surpass previous estimates of 21 to 29 million.

Hearing loss prevalence nearly doubled with every age decade, with women and blacks being significantly less likely to have hearing loss at any age. Lead researcher Frank Lin surmised that the female hormone estrogen, as well as the melanin pigment in darker skin, could have a protective effect on the inner ear and is worth exploring in future studies.